MacBook Won't Turn On

Screen got stepped on a while ago, worked but was cracked. Got one on eBay, installed it, and it worked okay for about 10 minutes, then when my back was turned, made a nice few second beep noise, and shut off.

Battery hasn’t worked in this thing for a while. I get a green light on the magnetic power adapter plug, and yellow/green flashing when the useless battery is installed.

Tried to reset the SMC to no avail. Did I cook the motherboard? Haha

Left it unplugged for 5 mins, and now it turns on again… jeeesssus